1. Field of the Invention
The present invention generally relates to an automatic blood pressure (BP) measuring apparatus and particularly to such an apparatus which has an inflatable pressure chamber for pressing a body portion of a subject.
2. Discussion of the Prior Art
There is known an automatic BP measuring apparatus of the type having (a) a pressing device which has an inflatable pressure chamber and which is set around a body portion of a subject, (b) a flexible hose, (c) a supply device for supplying pressurized fluid to the inflatable pressure chamber via the flexible hose so as to increase fluid pressure in the pressure chamber and thereby press the body portion of the subject, and (d) a relief-valve device for discharging the pressurized fluid in the inflatable pressure chamber if the fluid pressure in the pressure chamber exceeds a predetermined value as the pressurized fluid is supplied to the pressure chamber.
However, in the BP measuring apparatus of the above-described type, the relief-valve device is associated with the main body of the apparatus which is spaced apart from the pressing device or inflatable pressure chamber via the flexible hose provided therebetween. Accordingly, if the flexible hose is bent double, the relief-valve device may erroneously be operated, that is, placed in its operative position in which the device permits a decrease in the fluid pressure in the inflatable pressure chamber, though the fluid pressure in the pressure chamber may not have exceeded the predetermined value. In the case where the relief-valve device is provided with a manually operated reset mechanism for restoring the device from its operative position to its inoperative position, the operator or subject must operate the reset mechanism each time the relief-valve device is changed from its inoperative position to its operative position due to bending of the flexible hose.